Infectious bursal disease virus capsid protein VP3 interacts both with VP1, the RNA-dependent RNA polymerase and with viral double-stranded RNA

M.G.J. Tacken, B.P.H. Peeters, A.A.M. Thomas, P.J.M. Rottier, H.J. Boot

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    69 Citations (Scopus)

    Abstract

    Infectious bursal disease virus (IBDV) is a double-stranded RNA (dsRNA) virus of the Birnaviridae family. Its two genome segments are encapsidated together with multiple copies of the viral RNA-dependent RNA polymerase, VP1, in a single-shell capsid that is composed of VP2 and VP3. In this study we identified the domains responsible for the interaction between VP3 and VP1. Using the yeast two-hybrid system we found that VP1 binds to VP3 through an internal domain, while VP3 interacts with VP1 solely by its carboxy-terminal 10 amino acids. These results were confirmed by using a reverse-genetics system that allowed us to analyze the interaction of carboxy-terminally truncated VP3 molecules with VP1 in infected cells. Coimmunoprecipitations with VP1- and VP3-specific antibodies revealed that the interaction is extremely sensitive to truncation of VP3. The mere deletion of the C-terminal residue reduced coprecipitation almost completely and also fully abolished production of infectious virions. Surprisingly, these experiments additionally revealed that VP3 also binds to RNA. RNase treatments and reverse transcription-PCR analyses of the immunoprecipitates demonstrated that VP3 interacts with dsRNA of both viral genome segments. This interaction is not mediated by the carboxy-terminal domain of VP3 since C-terminal truncations of 1, 5, or 10 residues did not prevent formation of the VP3-dsRNA complexes. VP3 seems to be the key organizer of birnavirus structure, as it maintains critical interactions with all components of the viral particle: itself, VP2, VP1, and the two genomic dsRNAs.
    Original languageEnglish
    Pages (from-to)11301-11311
    JournalJournal of Virology
    Volume76
    DOIs
    Publication statusPublished - 2002

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